How to make a 440 Hz Speed Adjustment Test Cassette Tape - fix your deck, walkman, boombox

This video is not for professional use, but some of you may fix your cassette player/ recorder speed watching it. I'm aware that this is not the best way, but it can be useful to someone.
#testtape #cassettetape #speedadjustment

You can use free computer software to generate frequencies and record it on reference cassette deck, or...